The present invention relates generally to container strengthening systems, and, in particular, to liquefied gas injection systems used to strengthen containers.
Carbonated beverages, such as soft drinks and beer, are commonly packaged in metallic containers such as aluminum cans. The carbonation within the beverage exerts pressure on the containers, thereby increasing the strength of the container walls. However, it is generally desirable to further strengthen the containers in order to decrease the likelihood of damage to the containers as well as minimize the necessary thickness of the container walls.
One method used for strengthening containers is to deposit a liquefied gas such as nitrogen onto the beverage immediately prior to sealing the container. After sealing, the evaporated liquefied gas creates pressure within the container and also displaces oxygen from the headspace, thereby helping to prevent spoilage of the beverage. Many devices used to accomplish this result simply lay the liquefied gas onto the surface of the beverage, rather than forcibly injecting the liquefied gas into the beverage. This may suffice for non-carbonated beverages as well as some carbonated beverages. However, with a carbonated beverage such as beer that tends to produce a frothy head upon filling the container, liquefied gas deposited within the container tends to roll off the frothy head of the beverage and out of the container.
One solution would be to forcibly inject a liquefied gas such as nitrogen into the beverage utilizing a high-performance, quick-responding solenoid. However, due to the extremely cold temperatures involved in utilizing liquefied gas, a solenoid-controlled injector system must be carefully designed to avoid atomization of the liquid, which may occur when the liquefied gas is not properly passed through various inlets and/or outlets within the system. Furthermore, the pressure within the system must be carefully controlled in order to deliver a consistent amount of liquid nitrogen to each container in a high-speed filling operation.
The present invention is directed to a system for strengthening containers in a high-speed filling operation. The system may include a supply tank comprising an intake line in fluid flow relation with a source of liquefied gas and a back pressure regulator to control the pressure in the system. A liquid level control valve may be provided in fluid flow relation with the intake line in order to prevent liquefied gas from entering the back pressure regulator.
The system may also include an injector apparatus positioned at an angle to the containers being filled. The injector apparatus may comprise an intake line in fluid flow relation with the supply tank, and a chamber in fluid flow relation with the intake line. The pressure of liquefied gas within the chamber may be controlled by the back pressure regulator in the supply tank. The injector apparatus may also comprise an injector valve located within the chamber which includes a needle stem, a valve seat within a valve body, and a substantially straight outflow line which leads to the containers being filled. An adjustment device may also be provided for adjusting the position of the valve seat relative to the needle stem. The injector apparatus may further comprise a solenoid operatively connected to the needle stem, and a biasing device biasing the needle stem toward the valve seat. A heater may also be provided adjacent to the outflow line. The injector apparatus has an open operating state whereby the needle stem is positioned away from the valve seat, allowing liquefied gas within the chamber to flow out of the outflow line and into one of the containers. The injector apparatus also has a closed operating state whereby the needle stem is seated within the valve seat, blocking the liquefied gas within the chamber from entering the outflow line.
The system may further comprise a sensor operatively connected via a solenoid driver to the solenoid of the injector apparatus. Upon sensing the presence of a container, the sensor actuates the solenoid, thereby lifting the needle stem away from the valve seat and allowing liquefied gas to forcibly flow from the chamber through the outflow line at an angle into the container.